From 68e8b8ed787a8acafa3e987d52f6d415c5949ec6 Mon Sep 17 00:00:00 2001 From: Zqiang Date: Sun, 1 Nov 2020 17:07:53 -0800 Subject: [PATCH] kthread_worker: prevent queuing delayed work from timer_fn when it is being canceled commit 6993d0fdbee0eb38bfac350aa016f65ad11ed3b1 upstream. There is a small race window when a delayed work is being canceled and the work still might be queued from the timer_fn: CPU0 CPU1 kthread_cancel_delayed_work_sync() __kthread_cancel_work_sync() __kthread_cancel_work() work->canceling++; kthread_delayed_work_timer_fn() kthread_insert_work(); BUG: kthread_insert_work() should not get called when work->canceling is set. Signed-off-by: Zqiang Signed-off-by: Andrew Morton Reviewed-by: Petr Mladek Acked-by: Tejun Heo Cc: Link: https://lkml.kernel.org/r/20201014083030.16895-1-qiang.zhang@windriver.com Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- kernel/kthread.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/kthread.c b/kernel/kthread.c index b786eda90bb5..2eed853ab9cc 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -863,7 +863,8 @@ void kthread_delayed_work_timer_fn(struct timer_list *t) /* Move the work from worker->delayed_work_list. */ WARN_ON_ONCE(list_empty(&work->node)); list_del_init(&work->node); - kthread_insert_work(worker, work, &worker->work_list); + if (!work->canceling) + kthread_insert_work(worker, work, &worker->work_list); spin_unlock(&worker->lock); }